ANN ARBOR—Researchers at the University of Michigan havecreated crystals that can be organized into a structure that mimicsenamel of human teeth, a step toward creating fillings to replace thematerial that’s been destroyed.

Research investigator Haifeng Chen’s laboratory creation is reportedin an article in the current issue of the Journal of Colloid andInterface Science.

Chen uses a simple idea to explain why he’s excited about simulatingthe hard, white exterior of teeth. “If you have a cavity and you havetwo choices of a material to fill a tooth in your mouth—one that’ssimilar to what’s in your own teeth, and one that’s not—which wouldyou choose?”

Materials now used to fill cavities all have some drawbacks. Forexample, porcelain is very hard, which helps it last but also causeswear on teeth that come into contact with one that’s been filled.Real enamel contains fluoride and acts as a reservoir of thenaturally occurring compound that can help fight tooth decay.Synthesized enamel would mimic that ability.

Brian Clarkson, chair of cariology, restorative sciences andendodontics and the Clifford T. Nelson Professor of Dentistry, issenior author on the paper. He and Chen, a research investigator atthe School of Dentistry, worked on the project with Kai Sun and JohnMansfield at the U-M Electron Microbeam Analysis Laboratory, whereChen also has an appointment.

Clarkson and Chen met while Clarkson was on sabbatical a few yearsago in Leeds, England. “I was very impressed with him—not just histechnical ability, but his thought processes. He thinks very welloutside of the box,” Clarkson said of the young nanotechnologychemist.

Later, when Chen came to U-M, he visited Clarkson holding a journalarticle about barium chromate crystals. “He pointed to the pictureand said, ‘what do these look like to you?’ And I said, ‘they looklike enamel crystals.’ He said, ‘I can make that in the lab.'”

True to his word, Chen quickly created crystals in the lab with thesame chemical composition as natural enamel. “I’d never seen singleenamel crystals made in the lab. I was totally impressed,” Clarksonrecalled.

The next step was organizing individual crystals into a prism, sortof like taking individual bricks and building them into a wall.

“Enamel is special—the cells in the mature enamel are already dead,unlike bone or skin. Mature enamel is pure chemicals, so we thinkthere might be a pure chemical way to create enamel,” Chen said.

From building a prism, Chen and Clarkson now want to build realisticenamel structures.

Clarkson believes it’s possible they could have an enamel-likecomposite within a year, and produce crowns suitable for repairingdecayed teeth within about four years. Perhaps even before crowns,they could produce thin films that could act as a sort of enamelbandage over a cavity that’s just begun.

Application of synthetic enamel isn’t limited to filling cavities.Clarkson said he sees potential for use in bone repair and boneaugmentation. For example, if someone is in an accident and has abone damaged beyond what the body can naturally repair, addingsynthetic crystals could help heal it.

“Enamel is the hardest substance in the body,” Clarkson said. “If wecan make a similar structure to it, we can find many applications forit.”

Dentists have long worked on finding better, more durable ways tofill cavities in teeth—from stone chips to metals and amalgams.Synthesizing enamel is just one way researchers at the U-M School ofDentistry are continuing this work on better materials for healingwounds, including growing tongue tissue in a Petri dish and workingon tissue-engineered bone implants infused with therapeutic genes tohelp spur growth of new supporting tissue.

The Chen/Clarkson collaboration is funded by the National Instituteof Dental and Craniofacial Research, part of the National Institutesof Health, U-M’s Technology Transfer office has filed a patentapplication on the process with which to manufacture these crystals.

Related links:

Clarkson’s faculty profile

Journal of Colloid and Interface Science

Chen participated in a regenerative medicine showcase at U-M in May;read a synopsis of his work in this PDF of the program

U-M Tech Transfer

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More images >Clarkson’s faculty profileJournal of Colloid and Interface Scienceread a synopsis of his work in this PDF of the programU-M Tech Transfer